Datasheet

Wcta
8:1MUX
WCT1[2:0]
IN4N
IN4P
IN3N
IN3P
IN2N
IN2P
IN7N
IN7P
IN6N
IN6P
IN5N
IN5P
IN1N
IN1P
Wctb
8:1MUX
WCT2[5:3]
Wctc
8:1MUX
WCT2[2:0]
ToChannel
PGAs
ADS1298
avF_ch6 avF_ch5 avF_ch7
avF_ch4
ToChannel
PGAs
ADS1294, ADS1294R
ADS1296, ADS1296R
ADS1298, ADS1298R
www.ti.com SBAS459I –JANUARY 2010–REVISED JANUARY 2012
Augmented Leads
In the typical implementation of the 12-lead ECG with eight channels, the augmented leads are calculated
digitally. In certain applications, it may be required that all leads be derived in analog rather than digital. The
ADS1298/8R provides the option to generate the augmented leads by routing appropriate averages to channels
5 to 7. The same three amplifiers that are used to generate the WCT signal are used to generate the Goldberger
Central Terminal signals as well. Figure 56 shows an example of generating the augmented leads in analog
domain. Note that in this implementation it takes more than eight channels to generate the standard 12 leads.
Also, this feature is not available in the ADS1296/6R and ADS1294/4R.
Figure 56. Analog Domain Augmented Leads
Right Leg Drive with the WCT Point
In certain applications, the out-of-phase version of the WCT is used as the right leg drive reference. The
ADS1298 provides the option to have a buffered version of the WCT terminal at the RLD_OUT pin. This signal
can be inverted in phase using an external amplifier and used as the right leg drive. Refer to the Right Leg Drive
(RLD DC Bias Circuit) section for more details.
Copyright © 2010–2012, Texas Instruments Incorporated Submit Documentation Feedback 61
Product Folder Link(s): ADS1294 ADS1294R ADS1296 ADS1296R ADS1298 ADS1298R